Introduction to the CohortThe Chicago Health and Aging Project (CHAP) is a longitudinal study of aging and dementia based in three neighborhoods in Chicago, Illinois, USA. Based on a complete census of these neighborhoods conducted in 1993-1997, investigators recruited 6,158 adults, aged 65 and older, to participate, 3,838 of whom were deemed cognitively intact either by cognitive assessment or clinical evaluation. After the enrollment period, the CHAP pursued a complex strategy for follow-up evaluations, interviewing all participants about every three years and conducting in-depth clinical evaluations among a stratified random sample of participants at each of these cycles. At enrollment, members of the disease-free cohort were 73.6 years old on average (SD=6.1); 60% were female.

Ethnicity BreakdownAt baseline, 60% of the cohort members were African-American, and most of the remaining members were white.